Diabetes mellitus is a disease accompanied by a continuous hyperglycemic state and is said to occur as a result of action of many environmental factors and genetic factors. Main controlling factor for blood sugar is insulin and it has been known that hyperglycemia occurs when insulin becomes deficient or when various factors for inhibiting the action of insulin (such as genetic factor, lack of exercise, obesity and stress) become excessive.
Diabetes mellitus has two main types and is classified into insulin-dependent diabetes mellitus (IDDM) and non insulin-dependent diabetes mellitus (NIDDM). 95% or more of Japanese diabetic patients are said to be NIDDM and an increase in the number of patients due to changes in life style is becoming a problem.
With regard to the therapy of diabetes mellitus, diet therapy, therapeutic exercise and improvement in obesity are mostly conducted in mild cases and, upon progress, administration of oral agent for diabetes (for example, promoters for secretion of insulin such as sulfonylureas and potentiators for insulin sensitivity which potentiate sensitivity of insulin) is conducted. In severer cases, administration of insulin preparations is conducted. However, the above-mentioned insulin secreting action and sensitivity potentiating action are believed to be of an entirely different mechanism and, if compounds which have both of those actions are created, it is expected that they will be the therapeutic agents for diabetes mellitus having new mechanism, having extremely high usefulness and being able to conduct a higher blood sugar control. BRL 35135 [methyl (4-(2-((2-(3-chlorophenyl)-2-hydroxyethyl)amino)propyl)phenoxy)acetate] has been reported as a compound having both those actions (for example, Br. J. Clin. Pharmacol., 42, 291-300, 1996) but its effect is not sufficient and its development as a drug has been ceased already.
On the other hand, substituted phenylsulfonamide derivatives represented by the following general formula are described in EP 611003 and are mentioned to be useful for treating obesity, hyperglycemia, etc. due to their selective stimulating action to .beta..sub.3 -adrenaline receptor in human being. However, there is no disclosure at all for insulin secretion promoting action and insulin sensitivity potentiating action of those compounds. ##STR2## (Refer to the above-mentioned patent for the symbols in the formula.)